chore: snapshot working tree - pty_exited notifications + in-flight inference WIP

feat(booterm): structured pty_exited WS notifications. Plan-validated, impl-validated, code-reviewed green (contracts build clean, contracts test 29/29, booterm + web typecheck clean).

wip: in-progress inference/provider refactor (agents.ts, provider.ts, new llama-providers.ts, removed llama-args-validator), plus arena, dispatcher, compaction, schema changes.

openspec: pty-exit-notifications complete; x-agent-flags planned (not yet implemented).

apps/control/src/services/fleet-state.ts

@@ -0,0 +1,89 @@
+export interface HostConfig {
+  providerId: string;
+  baseUrl: string;
+  enabled: boolean;
+}
+
+export interface FleetState {
+  hosts: Map<string, HostState>;
+}
+
+export interface HostState {
+  providerId: string;
+  liveness: 'connected' | 'reconnecting' | 'down';
+  lastSeenAt: Date | null;
+  seq: number;
+  /** Host-level inflight total (the fork's SSE publishes only a total, not per-model). */
+  inflightTotal: number;
+  models: Map<string, ModelState>;
+}
+
+export interface ModelState {
+  model: string;
+  state: string;
+  ts: Date;
+  ttlDeadline: Date | null;
+  inflight: number;
+}
+
+export interface SnapshotData {
+  hosts: Array<{
+    providerId: string;
+    liveness: 'connected' | 'reconnecting' | 'down';
+    lastSeenAt: string | null;
+    seq: number;
+    models: Array<{
+      model: string;
+      state: string;
+      ts: string;
+      ttlDeadline: string | null;
+      inflight: number;
+    }>;
+  }>;
+  requests?: Array<{
+    id: number;
+    providerId: string;
+    ts: string;
+    model: string | null;
+    reqPath: string | null;
+    statusCode: number | null;
+    durationMs: number | null;
+  }>;
+  perfSamples?: Array<{
+    providerId: string;
+    ts: string;
+    gpu: unknown;
+    sys: unknown;
+  }>;
+}
+
+// ─── helpers for tests ──────────────────────────────────────────────────────
+
+export function createFleetState(): FleetState {
+  return { hosts: new Map() };
+}
+
+export function ensureHostState(fleet: FleetState, providerId: string): HostState {
+  let state = fleet.hosts.get(providerId);
+  if (!state) {
+    state = {
+      providerId,
+      liveness: 'down',
+      lastSeenAt: null,
+      seq: 0,
+      inflightTotal: 0,
+      models: new Map(),
+    };
+    fleet.hosts.set(providerId, state);
+  }
+  return state;
+}
+
+export function stampLastSeen(state: HostState): void {
+  state.lastSeenAt = new Date();
+}
+
+export function incrementSeq(state: HostState): number {
+  state.seq += 1;
+  return state.seq;
+}